1. Field of the Invention
This invention relates to a color toner to be used for image formation in electrostatography, including electrostatic copying electrophotography, etc.
2. Description of the Prior Art
Heretofore, various methods for electrophotography have been disclosed in U.S. Pat. No. 2,297,691, Japanese Patent Publications No. 23190/1977 and No. 24748/1978. These methods generally comprise utilizing a photoconductive material, forming electrostatic images on photosensitive members of the photoconductive material by various means, then developing the latent images with a toner, followed by transfer of the toner images onto papers or other materials, as desired, and thereafter fixing the images by heating, pressurization or with the use of solvent vapor. Also, for obtaining multi-color images, the original copy is exposed to light through a color resolution filter, the above electrophotographic steps are repeated by use of color toners, respectively, of yellow, magenta and cyan, and the toner images are successively overlapped to give color images.
For such color toners, while various characteristics are required similarly as in the case of a black toner for monochromatic copying, such as excellent charging characteristic, small extent of dependency on environment, small extent of degradation on repeated continuous usage and others, they are further required to satisfy characteristics inherent in color toners as indispensable characteristics, such as good spectral reflection characteristic, good color mixing characteristic, high degree of transparency, etc.
However, due to limited available materials in order to obtain good hue, transparency, etc., other characteristics including charging characteristic and durability cannot sufficiently be satisfied. Thus, under the present situation, improvements of color toners are incessantly sought after.